### Theory:

John Dalton was born to a poor weaver's family in England in $$1766$$. At the age of twelve, he started his career as a teacher. Then, he became a school principal seven years later.

Dalton moved to Manchester in $$1793$$ to teach mathematics, physics, and chemistry at a university.

He taught and did study there for the majority of his time. He proposed his atomic theory in $$1808$$, which was a watershed moment in the study of matter.

John Dalton's atomic theory was the first complete attempt to describe all matter in terms of atoms and their properties.

According to John Dalton, all matter, whether an element, a compound or a mixture, is composed of tiny particles called atoms.

Atoms can neither be created nor destroyed.

The following postulates are proposed by John Dalton:
• All matter is made of very tiny particles called atoms.
• Atoms are indivisible particles, which cannot be created or destroyed in a chemical reaction.
• Atoms of a given element are identical in mass and chemical properties.
• Atoms of different elements have different masses and chemical properties.
• Atoms combine in the ratio of small whole numbers to form compounds.
• The relative number and kinds of atoms are constant in a given compound.
Dalton's atomic theory
From Dalton's atomic theory, we get an idea about an atom. But, we should know what an atom is made up of. In the next lesson, we will explore more about the atom.